Thanks for that, the description was quite helpful, so at least I know I was on the right track. I messed around a little more, seeing if maybe I could detach and reattached the mesh (in case it was the old behaviour), but that wasn’t it. It just seems to be an issue with the way fixed/unfixed bodies are handled by physics: you can’t move the fixed root without it moving all the other bodies too. I posted on answerhub, and made a simple demonstration video, so hopefully one of the devs will see it and can explain the system, and how to get around it. I’ll let you know if there’s any answer Issue blending from physics into animation - World Creation - Unreal Engine Forums